Downloaded from https://www.everyspec.com MIL-STD-810D 19 Jllly1983’” The turbulent boundary layer is the most significant source of aero-acoustic loads Fecause it is always present during flight and acts on the total surface area’of ‘thestore over a broad frequency range’which inoludesresonant frequencies of electronic components and structural parts. The intensity of ~~ the tur,bu~ent.boundary layer pressure fluctuation and resulting store vibration primarily depends on flight dynamic pressure, q, a function of flight speed and altitude: q=* Where: 2 q dynamic pressure’(pounds per sq. ft.) k .
ratio of specific heats (* 1.4 for air ) ph = ambient pressure as a funotion of altitude (pounds Per Sq. ft.) M = Mach number Store vibration also”includes lower frequencies (usually less than 100 Hz) mechanically transmitted from the aircraft through the storets support ! mectianiam. LOW frequency vibration is discussed in I-3.~.2. . I-2.2.b ~. Operating stresses are ueually estimated becauee the service conditions (e.g., on..timeloff-time, aircraft power fluctustiona) are seldom meaaured and recorded. This stress cannot be omitted, unless the store‘has no operating mode while oarried on aircraft.
I-2.2.5 In combined environments testing, moisture often condenses on the teat item-during transitions from”low to high.temperatures. Its presence, although uncontrolled, is useful aa’a test condition to indicate leakage or sensitivity to moisture. Uhere humidity or corrosion problems are expected, separate tests are advised. ,. I-3 FOR ~ AND ~ .,. This,method should be applied only‘by qualified .peraonnelat the end of the tailoring process described in section 4 cf this standard. a. This‘methodapplies to reliability-relatedtesting of externally carried aircraft’atores (see table 523.0-1). ., -. .,. b. ~.
This method is intended primarily for the electronics and electromechanical assemblies within the Store. C. &gUQDQQ. This method applies the environmental stresses occuring in the final phases of the storets logistic cycle,’and when used in combination “. with other test methods, should ‘followthoee methods. ,d. Unlike the other methods in this standard, this methoti‘containsno step-by-step procedure for generating yalid teat data. The vibro/acoustic/temp&ratwe environment is too complex, and the variety of ~. equipment applications too great, for such’detailed instructions to be given’ here.
Instead, this method provides guidance f’orwriting a test procedure which will be more or leas unique for the item under consideration. MRTHOD 523.0 523.0-3 19 July 1983 ,,